The present invention relates to an elevator comprising a car, a drive motor driving the car, a motor drive unit for controlling the drive motor and supplying power thereto, an encoder for sensing movement of the car, an elevator rescue system for rescue operation in case of an emergency situation, and particularly for moving a car to a landing in case of an emergency situation.
Such an elevator is known in the prior art for example with the applicant's GEN2® elevator system which uses two encoders, one for normal and one for rescue operation with the encoder for rescue operation being connected to the service panel board of the elevator rescue system. Such a rescue encoder is only used for visualization of the car movement in order to provide the qualified person operating the service panel board in case of an emergency with an indication of the direction of movement and possibly a warning in case of overspeed. Therefore, a low resolution, low cost type encoder is used as the rescue encoder.
The most common emergency situation is due to a power failure in the main power supply to the elevator. In such a situation the power to the drive motor is interrupted and the brake falls in and stops the movement of the elevator car independent from the position thereof in the elevator shaft. Accordingly, the passengers are trapped in the elevator car. Other emergency situations can be due to defects in the elevator itself, for example in the safety chain, the elevator control, etc. In such an emergency situation it is mandatory to free the passengers from the elevator car as soon as possible.
For normal operation, the encoder typically is an encoder of the high resolution type in order to provide exact data on the speed and the position of the elevator car to the elevator control. Typically, such encoder is wired to the motor drive unit, but not to the service panel board or any other components of the elevator rescue system. Accordingly, such elevator system comprises two encoders of different functional requirements which are wired to different components of the elevator system.
Thus it is the object of the present invention to simplify existing elevator systems, to reduce the number of individual parts and to reduce costs while maintaining safety standards.